Periodic detection for railway is very important for reasonable arrangement and maintenance in low cost in rail transportation. On the one hand, at the early stage of rail wear and distortion, railway detection contributes to making reasonable schedule of railway maintenance to avoid dangerous situation, on the other hand, effective railway detection establishes foundation for railway detection from periodic maintenance to state maintenance, thereby making full use of limit human and instrument resource and saving cost of rail maintenance effectively.
At present, many research institutes and scholars at home and abroad have made research on detection methods for rail wear and developed various measurement devices. These measurement devices can be divided into contact devices and non-contact devices according to detection mode. Among them, the contact measurement devices have high measurement precision, but the complex operation and low efficiency make them only suitable for static measurement, therefore they are mainly used for studying rail wear resistance performance in labs, and not suitable for on-line measurement.
The non-contact measurement devices are suitable for dynamic measurement. Chinese Patent Application Serial No. 200510123725.0, titled “Dynamic Measurement Device and Method for Rail Wear Based on Laser Vision” published a device which could measure rail vertical wear and horizontal wear only by placing a single-line vision sensor at the inner side of rail. The device enhances the measurement efficiency of rail wear, reduces the cost and improves the operability and convenience of engineering application. However, the vision sensor in the device only projects one light plane, therefore each image only includes one rail cross-section feature profile, which wastes a great deal of image information and consumes a great deal of time for image processing.
In recent years, with the acceleration of railway, the great development of and heavy-duty transportation, the great increase of passenger transport and goods traffic, and the density of traveling trains, the situation of rail wear is more and more serious. It can be seen from the analysis above that the sample rate and measurement precision of the current rail wear measurement equipments are not competent for corrugation wear measurement because of the limitation of the performances of image sensing and acquisition hardware devices. Therefore, the worn rails can not be maintained and replaced in time, which will result in higher transportation cost and affect transportation safety directly, even cause fatal accident.
At present, for the measurement of corrugation wear, the methods at home and abroad are generally divided into two types: inertia reference method and chord measurement method. Inertia reference method measures corrugation wear by axial accelerometer. Because this method requires time double integration to get wear value, it has the drift problem for long time integration. It is difficult that measured values of chord measurement method accord with real values because the transform function doesn't equal to 1 constantly and has principle error. Therefore, neither of them can measure corrugation wear precisely.